1. Field of the Invention
The present invention relates to a current-carrying device for an EGR (Exhaust Gas Recirculation) valve device comprising for example a recycling system for exhaust gases.
2. Description of Related Art
Conventionally an EGR valve device has been used with a step motor to open and close valves. However use of a DC motor unit instead of a step motor has developed in order to avoid reductions in reliability, response characteristics and limits in the resolution of valve aperture regulation. FIG. 1 is a partial perspective view of a current carrying device of a conventional EGR valve device. FIG. 2 is a partial cross sectional view of a sensor power supplying unit 1 shown in FIG. 1. This type of EGR valve device uses a DC motor unit to drive valves. In FIG. 1, reference numeral 1 denotes a sensor power supplying unit which supplies power to a direct current(DC) motor and a sensor. A valve position is detected by the sensor. 2 denotes a power supply terminal which comprises a motor power supply terminal for supply of power to the DC motor unit and a sensor power supplying unit terminal for supply of power to the sensor in order to detect valve position. 3 denotes a power supply terminal cover which covers the power supply terminal 2. 4 denotes a concave portion formed in an abutting face la with the sensor power supplying unit 1 on the DC motor unit side. 5 denotes a connecting terminal for connecting the motor power supply terminal of the power supply terminal 2 to the DC motor unit. The connecting terminal 5 is formed in the concave portion 4.
6 denotes a DC motor unit. 7 denotes each of a plurality of receiving connectors formed on the DC motor unit 6 of a position at which the receiving connector 7 can be tightly engaged with the connecting terminal 5. 8 denotes each of a plurality of motor brush pressing plate springs, which are connected with the receiving connectors 7. 9 denotes each of a plurality of motor brushes. Each motor brush 9 is fixed to one face of the tip of the motor brush pressing plate spring 8 and is connected to a motor power supply terminal 2b discussed below. 10 denotes a disk-shaped feeding unit which comprises a plurality of commutator pieces and a plurality of slip rings. The disk-shaped feeding unit 10 is arranged in the DC motor unit 6 and rotates together with a rotor (not shown) of the DC motor unit 6.
In FIG. 2, reference numeral 2a denotes a sensor power supplying unit terminal and sensor signal output terminal, and 2b is a motor power supply terminal. 11 denotes a sensor for detecting valve position.
FIGS. 3A and 3B show a current carrying device in a conventional EGR valve device which comprises coils of the stator and which has a disk-shaped feeding unit which comprises the commutator pieces and the slip rings. In FIGS. 3A and 3B, those components which are the same or similar to those shown in FIG. 2 are denoted by the same numerals and additional description will be omitted. Each motor brush 9 which is fixed to the motor brush pressing plate spring 8 is connected electrically with the motor power supply terminal 2b through a connecting terminal 5 and the receiving terminal 7.
10 denotes the disk-shaped feeding unit which comprises the commutator pieces 15 and the slip rings 16 formed in a concentric shape on its surface. 13 denotes each of a plurality of motor brushes, 12 denotes each of a plurality of motor brush pressing plate spring members. Each motor brush 13 is tightly fitted to one tip surface of one motor brush pressing plate spring member 12. A DC current is supplied from the motor power supply terminal 2b to each motor brush 13 through one motor brush 9, and a DC current commutated by one commutator piece 15 of the disk-shaped feeding unit 10 is supplied to the coil of the stator through the motor brush 13. The motor brush pressing plate spring members 8, to which the motor brushes 9 are tightly fitted, and the motor brush pressing plate spring members 12, to which the motor brushes 13 are tightly fitted, are arranged on the periphery of the disk-shaped feeding unit 10 so as to be electrically insulated from each other. The motor brush pressing plate spring member 8 and the motor brush pressing plate spring members 12 extend from above the disk-shaped feeding unit 10 to fixed positions on the slip rings 16 or the commutator pieces 15 formed on the surface of the disk-shaped feeding unit 10 and pushes the motor brushes 9, 13 tightly fitted on the tip onto the surfaces of the slip rings 16 or the commutator pieces 15. Therefore, the motor brush pressing plate spring member 8 press the motor brushes 9 so as to make the motor brushes 9 slide on the surfaces of the commutator pieces 15, and the motor brush pressing plate spring members 12 press the motor brushes 13 so as to make the motor brushes 13 slide on the surfaces of the slip rings 16.
The operation of the current carrying device of the conventional EGR valve device will be described below.
In this type of EGR valve device, the sensor power supplying unit 1 abuts with the upper end of the DC motor unit 6. Abutment is required in order for the connecting terminal 5 in the concave portion 4 formed on the abutting face 1a on the power supply 1 of the DC motor unit 6 to make the connecting terminal 5 tightly engage with the receiving connector 7. As a result, the motor power supply terminal 2b of the sensor power supplying unit 1 is electrically connected with one commutator piece 15 of the disk-shaped feeding unit 10 of the DC motor unit 6.
The sensor 11 detects the position of a valve (not shown) which is formed on the side of the DC motor unit 6 and outputs a signal from the sensor signal output terminal 2a as an electrical signal.
Since the current carrying device of the conventional EGR valve device is comprised as above, it is necessary for the connecting terminal 5 of the sensor power supplying unit 1 to tightly engage with the receiving connector 6 of the DC motor unit 6 in order to assemble the sensor power supplying unit 1 with the DC motor unit 6. Thus it is difficult to complete the assembly operations of the sensor power supplying unit 1 and the DC motor unit 6 in a short time. Furthermore the problem has arisen that the structure of the current carrying device is complicated by the necessity to provide the connecting terminal 5 of the sensor power supplying unit 1 and to provide the receiving connector 7 of the DC motor unit 6.
The present invention is provided to solve the above-described problem, and the object of the present invention is to provide a current carrying device for an EGR valve device which facilitates assembly operations of the sensor power supplying unit and the DC motor unit and which simplifies the current carrying structure for the DC motor unit.
A current carrying device for an EGR valve device according to the present invention comprises a plurality of power supply motor brushes assembled on a sensor power supplying unit so as to connect each power supply motor brush with a power supply terminal of the sensor power supplying unit and to make each power supply motor brush be in contact with a commutator piece of a feeding unit arranged in the DC motor unit, and a plurality of coil feeding unit motor brushes, each of which is in contact with a slip ring of the feeding unit, for respectively supplying a current, which is supplied from one power supply terminal through one power supply motor brush and is commutated by one commutator piece, to a coil of a stator of the DC motor unit.
With such an arrangement, it is not necessary to provide a connecting element such as a connector between each power supply terminal of the sensor power supplying unit and the power supply motor brush. The current carrying structure which supplies power to the DC motor from each power supply terminal is simplified and assembly operations with the sensor power supplying unit and the DC motor are facilitated.
In a current carrying device for an EGR valve device according to the present invention, the coil feeding unit motor brushes are arranged in the DC motor unit.
With such an arrangement, the coil feeding motor brushes can be assembled into the DC motor unit in an assembly process for the DC motor which is separate from the assembly process for the sensor power supplying unit. It is possible to treat the coil power supply motor brushes as integrated with the DC motor. Assembly operations of the sensor power supplying unit and the DC motor are facilitated. The current carrying structure to the DC motor is simplified.
In a current carrying device for an EGR valve device according to the present invention, the coil feeding unit motor brushes are arranged in the sensor power supplying unit.
With such an arrangement, assembly operations of the sensor power supplying unit and the DC motor are facilitated and the current carrying structure to the DC motor is simplified.
A current carrying device for an EGR valve device according to the present invention further comprises coil feeding connection means, which is arranged between the sensor power supplying unit and the DC motor unit, for supplying a current commutated by each commutator piece from the sensor power supplying unit to the corresponding coil of the stator of the DC motor unit through the corresponding slip ring and the corresponding coil feeding motor brush connected to the commutator piece.
With such an arrangement, it is possible to assemble the power supply motor brushes and the coil power supply motor brushes in an integrated manner into the sensor power supplying unit during the assembly process of the sensor power supplying unit. It is possible to treat the power supply motor brushes and the coil power supply motor brushes as integrated with the sensor power supplying unit. Assembly operations of the sensor power supplying unit and the DC motor are facilitated and the current carrying structure to the DC motor is simplified.
In a current carrying device for an EGR valve device according to the present invention, the power supply motor brushes are arranged at positions of the sensor power supplying unit, the tip of each power supply motor brush abuts perpendicularly with the corresponding commutator piece of the disk-shaped feeding unit of the DC motor unit in a state that the sensor power supplying unit is assembled into the DC motor unit, the coil feeding motor brushes are arranged at positions of the sensor power supplying unit, and the tip of each coil feeding motor brush abuts perpendicularly with the corresponding slip ring of the disk-shaped feeding unit of the DC motor unit in a state that the sensor power supplying unit is assembled into the DC motor unit.
With such an arrangement, since the commutator pieces and the slip rings are formed on the disk-shaped feeding unit, the surface contacting each power supply motor brush and the corresponding coil feeding motor brush can be increased. Thus it is possible to increase the interval between each power supply motor brush and the corresponding coil power supply motor brush formed on the sensor power supplying unit. Arrangement of the coil power supply motor brushes and the power supply motor brushes is facilitated. The power supply motor brushes and the coil feeding motor brushes are formed on the sensor power supplying unit. Each coil power supply motor brush is connected with the coil of the stator of the DC motor by the coil power supply connection means. Thus the current carrying structure supplying electrical power from each power supply terminal to the DC motor is simplified and assembly operations of the sensor power supplying unit and the DC motor are facilitated.
In a current carrying device for an EGR valve device according to the present invention, the power supply motor brushes are arranged at positions of the sensor power supplying unit, the tip of each power supply motor brush abuts perpendicularly with the corresponding commutator piece of the ring-shaped feeding unit of the DC motor unit in a state that the sensor power supplying unit is assembled into the DC motor unit, the coil feeding motor brushes are arranged at positions of the sensor power supplying unit, and the tip of each coil feeding motor brush abuts perpendicularly with the corresponding slip ring of the ring-shaped feeding unit of the DC motor unit in a state that the sensor power supplying unit is assembled into the DC motor unit.
With such an arrangement, since the commutator pieces and the slip rings are formed on the ring-shaped feeding unit, the surface contacting each power supply motor brush and the corresponding coil feeding motor brush can be increased. Thus it is possible to increase the interval between each power supply motor brush and the corresponding coil power supply motor brush formed on the sensor power supplying unit. Arrangement of the coil power supply motor brushes and the power supply motor brushes is facilitated. The power supply motor brushes and the coil feeding motor brushes are formed on the sensor power supplying unit. Each coil power supply motor brush is connected with the coil of the stator of the DC motor by the coil power supply connection means. Thus the current carrying structure supplying electrical power from each power supply terminal to the DC motor is simplified and assembly operations of the sensor power supplying unit and the DC motor are facilitated.